Reading about Billy Idol

For some strange reason, I was just reading the Billy Idol entry in Wikipedia. Wow - a few things about him:

• He's had a long, successful career
• He got a lot of mileage out of being a punk

And a question: how does one go from being in Siouxsie & the Banshees and Generation X to recording a CD full of Christmas songs (in 2006)? From punk to yuletide cheer? From original alternative to yuppie stocking stuffer?

People change. People grow. Amazing!